Manufacture of polytrimethylene ether glycol

Abstract

A process of manufacture of polytrimethylene ether glycol comprising:(a) polycondensing reactant comprising diol selected from the group consisting of 1,3-propanediol, 1,3-propanediol dimer and 1,3-propanediol trimer or mixtures thereof in the presence of acid polycondensation catalyst to form polytrimethylene ether glycol;(b) adding water to the polytrimethylene ether glycol to form an aqueous mixture;(c) heating the aqueous mixture to hydrolyze acid esters formed during the acid catalyzed polycondensation;(d) adding to the hydrolyzed aqueous mixture organic solvent that is miscible with polytrimethylene ether glycol to form (i) organic phase containing the polytrimethylene ether glycol and residual acid polycondensation catalyst from the polycondensing and (ii) aqueous phase;(e) separating the aqueous phase and the organic phase;(f) adding base to the separated organic phase to neutralize the residual acid polycondensation catalyst by forming salts of the residual acid polycondensation catalyst;(g) separating the organic phase into (i) liquid phase comprising the polytrimethylene ether glycol, the organic solvent and any residual water, and (ii) solid phase comprising the salts of the residual acid polycondensation catalyst and the base which is unreacted; and(h) removing the organic solvent and the residual water from the liquid phase to obtain polytrimethylene ether glycol.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an improved process for purifying polytrimethylene ether glycol.BACKGROUND OF THE INVENTION[0002]Polytrimethylene ether glycol and its uses have been described in the art. Preferred methods for preparation of polytrimethylene ether glycol involve acid catalyzed polycondensation of 1,3-propanediol. For example, U.S. Pat. No. 6,720,459, which is incorporated herein by reference, discloses a continuous process for preparation of polytrimethylene ether glycol from 1,3-propanediol using a polycondensation catalyst, preferably an acid catalyst.[0003]WO99 / 01496, which is incorporated herein by reference, discloses a process for the purification of polyethers includes the steps of (a) heating a polyether glycol with water for a time and at temperature sufficient to substantially hydryrolyze esters formed during polymerization, (b) separating the polyether from the water, and (c) subjecting the polyether recovered from step (b) to ...

AI Technical Summary

Benefits of technology

[0104]The data in Table 1 shows that the addition of solvent dramatically reduces the phase separation and filtration times while having no substantial effect on the properties of the polytrimethylene ether glycol. Moreover, the present invention also achieved significantly improved yields of the polymer.

Problems solved by technology

These ester groups act as emulsifying agents during the water washing process, thus causing the washing process to be difficult and time consuming, and causing incomplete acid removal.

This process has a disadvantage in that organic solvent ends up in both the aqueous and polymer (polyether polyol) phases.

It is undesirable to have a solvent present in the aqueous phase because the disclosed organic solvents are flammable and, thus, it is necessary to recover the organic solvent from the aqueous phase prior to reuse or disposal of the water and in order to reuse the organic solvent.

This process also has the disadvantage that the resulting polyether polyols contain base catalyst residues.